1. Field of the Invention:
The present invention relates to a suspended ceiling structure for rectangular filter elements comprising a framework with outer and inner U-shaped channels which slidingly fit together and are suspended on supporting tie rods in the upper ceiling, the channels being filled with a sealing fluid and being adapted to receive skirts which are arranged along the edges of the filter elements in order to support these elements and to form an airtight seal for the air which is below the filter elements and is intended to flow through them.
2. Discussion of the Background:
Suspended ceiling structures of the kind described above are previously known, e.g. through EP-A1 116 772. This known structure, however, is marred by several drawbacks. Thus, the joints which form connecting points in the latticework and consist of X-joints, tees or angles are provided with fastening means for the tie rods. This means that when the framework is to be erected the position of the tie rods in the upper ceiling has to be accurately marked since there is no possibility to move the positions of the fastening means in case a tie rod is erroneously positioned. Consequently, at the erection of such a known suspended ceiling structure the joints which form the intersection points in the framework have to be mounted whereupon the connecting channel portions which are supported by the intersection joints can be introduced into the joint channels and fixed thereto by means of pop rivets. Such an installation is time-consuming and has to be preceded by accurate measurements to put the tie rods at correct locations in the ceiling. Neither is it aesthetically attractive to see the joint ends between the joint channels and the channels which interconnect the intersection points.
A further drawback is that holes are to be drilled in the channels by hand for lighting armature brackets or similar attachment means when lighting armature or other fittings are to be suspended in the framework.